Encyclopedia Astronautica
LAGEOS


American earth geodetic satellite. 2 launches, 1976.05.04 (Lageos) and 1992.10.22 (Lageos 2). The LAGEOS satellites were passive vehicles covered with retroreflectors designed to reflect laser beams transmitted from ground stations.

By measuring the time between transmission of the beam and reception of the reflected signal from the satellite, stations could precisely measure the distance between themselves and the satellite. These distances could be used to calculate station's positions to within 1-3 cm. Long term data sets could be used to monitor the motion of the Earth's tectonic plates, measure the Earth's gravitational field, measure the "wobble" in the Earth's axis of rotation, and better determine the length of an Earth day.

LAGEOS 1 was developed by NASA and was placed into a high inclination orbit to permit viewing by ground stations located around the world. LAGEOS 2 was a joint program between NASA and the Italian space agency (ASI), which built the satellite using LAGEOS 1 drawings and specifications, handling fixtures, and other materials provided by NASA.

LAGEOS 2's orbit was selected to provide more coverage of seismically active areas, such as the Mediterranean Basin and California, and may help scientists understand irregularities noted in the motion of LAGEOS 1. Ground tracking stations were located in many countries (including the US, Mexico, France, Germany, Poland, Australia, Egypt, China, Peru, Italy, and Japan) and data from these stations was available world-wide to investigators studying crustal dynamics. LAGEOS 1 also contained a message plaque addressed to human and other beings of the far distant future with maps of the Earth from 3 different eras - 268 million years in the past, present day, and 8 million years in the future (the satellite's estimated decay date).

Both satellites were spherical bodies with an aluminum shell wrapped around a brass core. The design was a compromise between numerous factors including the need to be as heavy as possible to minimize the effects of non-gravitational forces; while being light enough to be placed in a high orbit; and the need to accommodate as many retroreflectors as possible; and the need to minimize surface area to minimize the effects of solar pressure. The materials were chosen to reduce the effects of the Earth's magnetic field on the satellite's orbit. 426 cube-corner retroreflectors were imbedded in the satellites' surface. 422 of these were made of fused silica glass while the other 4 were made of germanium. The vehicles had no onboard sensors or electronics, and were not attitude controlled. Science was performed by reflecting laser light from the vehicle's 426 retroreflectors.

AKA: LAser GEOdynamics Satellite.
Gross mass: 405 kg (892 lb).
Height: 0.60 m (1.96 ft).
First Launch: 1976.05.04.
Last Launch: 1992.10.22.
Number: 2 .

More... - Chronology...


Associated Countries
See also
  • Delta The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Development began in 1955 and it continued in service in the 21st Century despite numerous candidate replacements. More...
  • Shuttle The manned reusable space system which was designed to slash the cost of space transport and replace all expendable launch vehicles. It did neither, but did keep NASA in the manned space flight business for 30 years. More...

Associated Launch Vehicles
  • Delta American orbital launch vehicle. The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Delta began as Thor, a crash December 1955 program to produce an intermediate range ballistic missile using existing components, which flew thirteen months after go-ahead. Fifteen months after that, a space launch version flew, using an existing upper stage. The addition of solid rocket boosters allowed the Thor core and Able/Delta upper stages to be stretched. Costs were kept down by using first and second-stage rocket engines surplus to the Apollo program in the 1970's. Continuous introduction of new 'existing' technology over the years resulted in an incredible evolution - the payload into a geosynchronous transfer orbit increasing from 68 kg in 1962 to 3810 kg by 2002. Delta survived innumerable attempts to kill the program and replace it with 'more rationale' alternatives. By 2008 nearly 1,000 boosters had flown over a fifty-year career, and cancellation was again announced. More...
  • Delta 2913 American orbital launch vehicle. Three stage vehicle consisting of 9 x Castor 2 + 1 x ELT Thor/RS-27 + 1 x Delta P /TR-201 + 1 x Star 37D More...
  • Shuttle American winged orbital launch vehicle. The manned reusable space system which was designed to slash the cost of space transport and replace all expendable launch vehicles. It did neither, but did keep NASA in the manned space flight business for 30 years. Redesign of the shuttle with reliability in mind after the Challenger disaster reduced maximum payload to low earth orbit from 27,850 kg to 24,400 kg. More...
  • Delta 2000 American orbital launch vehicle. The Delta 2000 series used Castor 2 strap-ons together with an Extended Long Tank core equipped with the more powerful RS-27 engine. This engine was derived from surplus H-1 engines intended for the Saturn IB booster of the Apollo programme. The Delta P upper stage was built by Douglas and used surplus Apollo lunar module engines from TRW. More...

Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • ASI Italian agency overseeing development of spacecraft. Agenzia Spaziale Italiano (Italian space agency), Italy. More...
  • Bendix American manufacturer of rockets and spacecraft. Bendix, USA. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Web Address when accessed: here.
  • McDowell, Jonathan, Launch Log, October 1998. Web Address when accessed: here.

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...
  • Vandenberg Vandenberg Air Force Base is located on the Central Coast of California about 240 km northwest of Los Angeles. It is used for launches of unmanned government and commercial satellites into polar orbit and intercontinental ballistic missile test launches toward the Kwajalein Atoll. More...
  • Cape Canaveral LC39B Shuttle, Saturn V, Saturn I launch complex. LC39A and LC39B, part of the Kennedy Space Center, were built on Merritt Island (north/northwest of the Cape) to support the Saturn V/Apollo lunar landing program in 1963-1966. The sites were modified in the last half of the 1970s to support the manned Space Shuttle program. More...
  • Vandenberg SLC2W Delta launch complex. Originally a Thor 75 SMS launch pad. Upgraded to a space launch complex in 1966. More...

LAGEOS Chronology


1976 May 4 - . 08:00 GMT - . Launch Site: Vandenberg. Launch Complex: Vandenberg SLC2W. LV Family: Delta. Launch Vehicle: Delta 2913. LV Configuration: Delta 2913 609/D123.
  • Lageos - . Payload: Lageos 1. Mass: 411 kg (906 lb). Nation: USA. Agency: NASA Huntsville. Class: Earth. Type: Geodetic satellite. Spacecraft: Lageos. USAF Sat Cat: 8820 . COSPAR: 1976-039A. Apogee: 5,947 km (3,695 mi). Perigee: 5,839 km (3,628 mi). Inclination: 109.9000 deg. Period: 225.50 min. LAGEOS (Laser Geodetic Satellite) was a very dense (high mass-to-area ratio) laser retroreflector satellite which provided a permanent reference point in a very stable orbit for such precision earth-dynamics measurements as crustal motions, regional strains, fault motions, polar motion and earth-rotation variations, solid earth tides, and other kinematic and dynamic parameters associated with earthquake assessment and alleviation. The performance in orbit of LAGEOS was limited only by degradation of the retroreflectors, so many decades of useful life can be expected. The high mass-to-area ratio and the precise, stable (attitude-independent) geometry of the spacecraft, together with the orbit, made this satellite the most precise position reference available. Because it is visible in all parts of the world and has an extended operation life in orbit, LAGEOS can serve as a fundamental standard for decades. Additional Details: here....

1992 October 22 - . 17:09 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39B. LV Family: Shuttle. Launch Vehicle: Shuttle. LV Configuration: Space Shuttle STS-52.
  • Lageos 2 - . Payload: Columbia F13 / Lageos 2 [Iris] / CTA. Mass: 400 kg (880 lb). Nation: Italy. Agency: ASI. Class: Earth. Type: Geodetic satellite. Spacecraft: Lageos. USAF Sat Cat: 22195 . COSPAR: 1992-070B. Apogee: 5,952 km (3,698 mi). Perigee: 5,616 km (3,489 mi). Inclination: 52.7000 deg. Period: 222.50 min. Summary: 60 cm diameter sphere with laser reflectors; deployed from STS-52 10/23/92..

Home - Browse - Contact
© / Conditions for Use